He looks both short and slight, and has a somewhat girlish face.
Here's James Holmes, the Aurora Colorado shooter from July of 2012:
Here is Elliot Rodger, the Santa Barbara shooter from May of 2014:
And here is Adam Lanza, of Newtown CT fame:
What do they all have in common? They're small, even frail, and appear to have low testosterone levels. It's pretty obvious that before they took a bunch of lives, nobody took much notice of them except perhaps to note what losers they were. None were athletic, and most were probably virgins. They were all disappointments to their parents, and unpopular with their peers.
And, wimps that they were, they all needed guns as equalizers.
In a way it makes sense that these guys would turn out to be killers, because they had nothing to lose. And they were all resentful, so they wanted to take others with them. Roof's bitterness was focused on black people; but his basic psychology was undoubtedly the same.
I wrote a sample article once before, about Adam Lanza, as an example of what a responsible media would say about these guys: emphasize what dweebs and losers they are. If these potential killers knew beforehand that their actions would cause them to be held up to public ridicule, most would just take their own lives, and leave the rest of us alone.